1840] WKITINGS OF JOSEPH HEXRY. 189 



ON A RECIPROCATING MOTION PRODUCED BY GALVANIC AT- 

 TRACTION AND REPULSION. 

 (Proceedings of the American Philosophical Society, vol. i, p. 301.) 

 Xovember 20, 1840. 



Prof. Henry described an apparatus for producing a re- 

 ciprocating motion by the repulsion in the consecutive parts 

 of a conductor, through -which a galvanic current is passing, 

 and made some remarks in reference to the electro-magnetic 

 engine invented by him in 1831,* and subsequently de- 

 scribed by Dr. Ritchie, of London. The machine referred 

 to had been applied recently by Prof Henry in his experi- 

 ments. 



ON THE EVOLUTION OF ELECTRICITY FROM STEAM, ETC. 



(Proceedings of the American Philosophical Society, vol. i, pp. 322, 824.) 



December 18, 1840. 



[Dr. Patterson called the attention of the Society to the 

 subject of the evolution of electricity from steam, mentioned 

 at the last meeting, and stated that the experiments made 

 lately in England had been successfully repeated by Mr. 

 Peale, Mr. Saxton, and himself, at the United States Mint. 

 - - - - He thought it most probable that the electricity, 

 in these experiments, was evolved by the condensation of 

 the steam. - - - - ] 



Prof. Henry stated that he had not seen the sparks from 

 steam ; but that he had obtained feeble electricity from a 

 small ball, partly filled with water, and heated by a lamp. 

 He agreed with Dr. Patterson in the opinion that the source 

 of the electricity was the change of state, — but from water to 

 vapor. There was however some doubt on the subject. 

 Pouillet had denied the evolution of electricity from the 

 evaporation of pure water. The facts were interesting, par- 

 ticularly on account of the great intensity of the electricity. 



*[Silliman's American Journal of Science, July, 1831, vol. xx, p. 340. — 

 Ante, page 54.] 



